Investments (Tables)

6 Months Ended

Jun. 30, 2016

Short-term Investments [Abstract]

Maturities for short-term investments

The estimated fair values of short-term investments, which approximate cost at June 30, 2016, are shown below by contractual maturity. Actual maturities may differ from contractual maturities because issuers of the securities may have the right to retire our investments without prepayment penalties.

(in millions)	Available-For-Sale
Due in one year or less	$	231
Due after one year through three years	854
Due after three years through five years	164
Due after five years	40
Total	$	1,289